Inhibin is a
peptide hormone produced by ovarian granulosa cells and testicular Sertoli cells. Ovarian granulosa cell and other
sex cord-stromal tumors usually exhibit positive immunohistochemical staining with antiinhibin
antibodies, and this may be valuable in differentiating these
neoplasms from histologic mimics. In the present study, we investigated the immunohistochemical staining of testicular
sex cord-stromal tumors using antiinhibin. Immunostaining with
CAM5.2,
vimentin,
S-100 protein,
desmin,
epithelial membrane antigen (EMA),
carcinoembryonic antigen (CEA), and
placental alkaline phosphatase (PLAP) also was performed because few studies have investigated in detail the immunophenotype of testicular
sex cord-stromal tumors. Fifteen of 16 Leydig cell
tumors exhibited strong positive staining with antiinhibin. A proportion of Leydig cell
tumors also stained positively with
CAM5.2 (7 of 16),
vimentin (14 of 16),
S-100 protein (10 of 16),
desmin (2 of 16) and
epithelial membrane antigen (4 of 16). Four of six testicular
sex cord-stromal tumors with varying degrees of Sertoli or granulosa cell differentiation were positive with antiinhibin, as were two of three
sex cord-stromal tumors that were unclassified. Some of these
tumors were positive with CAM 5.2,
vimentin,
S-100 protein,
desmin, and
epithelial membrane antigen. All
tumors were negative with
carcinoembryonic antigen and
placental alkaline phosphatase. The immunohistochemical findings show that, analogous to their ovarian counterparts, most testicular
sex cord-stromal tumors are immunoreactive with antiinhibin. Immunohistochemistry using this antibody as part of a panel may be valuable in confirming a diagnosis of testicular
sex cord-stromal tumor and in differentiating these
neoplasms from others that may mimic them.